1. Field of the Invention
The present invention relates to welding apparatuses using induction heating wherein work pieces to be welded are previously positioned for the purpose. More particularly, the invention relates to apparatuses for delivery of melting rings and valves to an inductor heater for hard-facing of valves for internal combustion engines by melting rings of heat-resistant alloys upon the working surface of the valves.
Most efficiently the invention can be employed at enterprises engaged in serial production of valves for internal combustion engines.
2. Description of the Prior Art
It is a known fact that to effect hard facing of a valve, an alloy ring is fitted onto its head, the valve is put in a vertical position and the above head with the ring fitted thereupon is placed into a high-temperature heater, for instance a high-frequency inductor.
At present, valves are hard-faced with the aid of devices wherein the fitting of a ring onto the valve head, the positioning of the valve in a vertical alignment and the delivering of the valve into the inductor are carried out by mechanical means, for instance a manipulator.
Despite the automation of the hard-facing process, there still remain possibilities to increase the efficiency of the above devices by shortening the time for assembling the work valve and ring, as well as by carrying out the above assembling at a time when the previous valve is being hard faced.
Also known in the art are apparatuses for hard-facing of valves for internal combustion engines, wherein work valves and the rings to be melted are fed to gravity. Such apparatuses are simple in construction and more efficient as compared with similar apparatuses wherein the assembling is performed by a number of mechanisms.
For instance, known in the art is an apparatus for hard-facing of valves for internal combustion engines comprising a means for assembling the work valve and the ring to be melted (cf. Swedish Pat. No. 7802954-3), including, a vertically positioned tubular body adjoined by gravity feed trays, one for feeding the work valves and the other for feeding the rings; a stop located under the tray for feeding the valves and intended for positioning the valve with its stem being upwardly directed; a receiver for receiving the rings and delivering them onto the valve stem; a pusher located under the tubular body and adapted to deliver the valve with the ring fitted upon its head into the inductor, and a mechanism for holding the valve therein.
To effect delivery of the valves inside the tubular body, the tubular body has a hole adjoined by the tray for feeding the rings to be melted, the receiver for receiving the rings is a kind of curtain inserted into the slot made in the tubular body below the hole for feeding the rings therein. The curtain is connected with a drive providing for its back-and-forward movement.
The pusher for feeding the rings is mounted on a slide and has a tubular body accomodate the valve with the ring fitted thereupon, the pusher slide being connected with the back-and-forward movement drive to provide that the pusher be placed alternately under the tubular body or the inductor.
The tray for feeding the rings has a complicated form which provides for vertically positioning the rings at the entry side of the tray and for its horizontally positioning at the exit side thereof. A separator for by-piece feeding the rings from a storage is mounted at the entry side of the tray for feeding the rings.
To feed the rings with a predetermined side turned in the direction of movement, i.e., to prevent the ring from turning over, there is provided another curtain inserted into the slot made in the tubular body above the aforementioned hole.
Despite the fact that the above apparatus has some advantages typical of the apparatuses using a gravity feed of workpieces to be welded, its application is limited which is due to the fact that the arrangement of the pusher on the slide connected with a drive and the necessity of mechanical processing of the tubular body to obtain various entries and exits for the valves and rings complicate the apparatus design.
In addition, the time spent for feeding successively the valves and rings to the tubular body, for fitting the ring in the receiver, as well as for moving the pusher to under the heater and then back to under the tubular body restrict the efficiency of the above apparatus.